Growing up in Southwest Philadelphia, Aissia Richardson would take the school bus on class trips and wonder why there were no seat belts.

Today, as a parent, she often asks herself the same question.

"We have a mantra when we go on family vacations with the kids," said Richardson, whose 10-year-old daughter, Yasmina, takes a daily one-hour bus ride to the Girard Academic Music Program in South Philadelphia. "The car doesn't move until they're buckled in."

During Yasmina's bus ride, Richardson said, "anything can happen." So, if state law can require Yasmina to wear a seat belt in her car, Richardson said, a state law, or a city ordinance, should require her daughter to wear one on the yellow bus.

Philadelphia City Council could take steps to make that happen today, as it is expected to pass an ordinance mandating lap-and-shoulder seat belts on all city school buses.

If Mayor Street signs the bill, 35,000 public, private, and charter school students on 1,370 bus routes would be required to buckle up by September 2008. Street could, however, exercise a "pocket veto" and simply fail to sign the bill before his term ends.

"You think about it, it is an important question to be raised," said Joyce Eubanks, director of legislation for Councilwoman Carol Ann Campbell, who introduced the bill in March.

Eubanks said she thought the city should be able to mandate seat belts on school buses for students in the state-controlled school district, but which has that legal authority - Council or the state legislature - is far from clear. Eubanks said the city and the state "would have to make some kind of agreement."

Philadelphia School District spokesman Fernando Gallard said in a statement that the district, which contracts all city buses, would work with the city to install seat belts "upon receipt of sufficient funds."

The national debate on seat belts in school buses has dragged on since 1977, when federal legislation tightened safety standards. Through a concept known as "compartmentalization," school buses were equipped with high, closely spaced, and well-cushioned seats, which limit passenger movement and impact. But Congress declined to mandate seat belts on large buses that hold 50 to 60 students.

States, including New York in 1987 and New Jersey in 1994, and local school districts have increasingly mandated seat belts on new buses over the last three decades at their own expense. School buses are the safest form of transportation because of their size and interior design, and have a fatality rate nearly six times lower than that of passenger vehicles, according to the National Highway Traffic Safety Administration (NHTSA).

But the agency called lap-and-shoulder seat belts the "optimum" protection in a report released Nov. 19 and encouraged greater use through increased highway funding and new guidelines after federal hearings in July.

The move was influenced by recent studies that have proven the advantages of seat belts. An American Academy of Pediatrics study last year revealed that previous national estimates on school bus-related injuries were grossly understated.

Recent National Transportation Safety Board studies, as well, show that the safety afforded from compartmentalization is "incomplete." The safety design, the reports show, do not protect children in side and rollover collisions.

In accidents, children "don't just fly into the padding like the feds would tell you," said Alan Ross, president of the National Coalition for School Bus Safety. "They smash into the walls, fly around like projectiles, and bounce like a pinball in a pinball machine."

The NHTSA, in its recent report, maintained that seat belts would reduce capacity on buses and force children into more dangerous forms of transportation. The agency and the bus industry also argue that reduced capacity would run up costs and essentially lead to an unfunded mandate.

"You can't anticipate the types of things that happen in life, and we're coming to the point where we're just throwing dollars at an issue and it's not going to make that much of a difference," said Wayne Johnston, president of the Pennsylvania Pupil Transportation Association.

Safety advocates have dismissed these claims, saying that the current "three-child-per-seat" capacity regulations are outdated and unrealistic. They also say that installations on newly purchased buses would be inexpensive.

There were 351 school bus accidents in the city last year, Gallard said, but most were minor. Statewide, there have been 1,733 school bus passenger injuries during the last five years, according to Pennsylvania Department of Transportation statistics, and 76 percent of them were classified as minor. There have been no fatalities.

"But if my kid's in the other percentile," said Jack Carr, assistant principal at the Girard music program, "then I want seat belts. That's worth it to me, and I'm sure it would be to any parent."

PennDot has never allocated highway funds to local school districts for seat belts because the money is targeted to high-fatality areas like DUIs and aggressive driving, said spokeswoman Danielle Klinger. But PennDot is currently reviewing the new NHTSA proposal, she said.

"Hopefully [the ordinance] will generate enough discussion in the state that the state will look at it," said Eubanks.

Contact staff writer Nick Pipitone at 215-854-5554 or npipitone@phillynews.com.